/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.coyote.http11.upgrade;

import org.apache.tomcat.util.net.NioChannel;
import org.apache.tomcat.util.net.NioEndpoint;
import org.apache.tomcat.util.net.NioSelectorPool;
import org.apache.tomcat.util.net.SocketWrapper;

import java.io.EOFException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.Selector;

public class NioServletInputStream extends AbstractServletInputStream {

	private final NioChannel channel;
	private final NioSelectorPool pool;

	public NioServletInputStream(SocketWrapper<NioChannel> wrapper,
	                             NioSelectorPool pool) {
		this.channel = wrapper.getSocket();
		this.pool = pool;
	}

	@Override
	protected boolean doIsReady() throws IOException {
		ByteBuffer readBuffer = channel.getBufHandler().getReadBuffer();

		if (readBuffer.remaining() > 0) {
			return true;
		}

		readBuffer.clear();
		fillReadBuffer(false);

		boolean isReady = readBuffer.position() > 0;
		readBuffer.flip();
		return isReady;
	}

	@Override
	protected int doRead(boolean block, byte[] b, int off, int len)
			throws IOException {

		ByteBuffer readBuffer = channel.getBufHandler().getReadBuffer();
		int remaining = readBuffer.remaining();

		// Is there enough data in the read buffer to satisfy this request?
		if (remaining >= len) {
			readBuffer.get(b, off, len);
			return len;
		}

		// Copy what data there is in the read buffer to the byte array
		int leftToWrite = len;
		int newOffset = off;
		if (remaining > 0) {
			readBuffer.get(b, off, remaining);
			leftToWrite -= remaining;
			newOffset += remaining;
		}

		// Fill the read buffer as best we can
		readBuffer.clear();
		int nRead = fillReadBuffer(block);

		// Full as much of the remaining byte array as possible with the data
		// that was just read
		if (nRead > 0) {
			readBuffer.flip();
			if (nRead > leftToWrite) {
				readBuffer.get(b, newOffset, leftToWrite);
				leftToWrite = 0;
			} else {
				readBuffer.get(b, newOffset, nRead);
				leftToWrite -= nRead;
			}
		} else if (nRead == 0) {
			readBuffer.flip();
		} else if (nRead == -1) {
			// TODO i18n
			throw new EOFException();
		}

		return len - leftToWrite;
	}

	@Override
	protected void doClose() throws IOException {
		channel.close();
	}

	private int fillReadBuffer(boolean block) throws IOException {
		int nRead;
		if (block) {
			Selector selector = null;
			try {
				selector = pool.get();
			} catch (IOException x) {
				// Ignore
			}
			try {
				NioEndpoint.KeyAttachment att =
						(NioEndpoint.KeyAttachment) channel.getAttachment();
				if (att == null) {
					throw new IOException("Key must be cancelled.");
				}
				nRead = pool.read(channel.getBufHandler().getReadBuffer(),
						channel, selector, att.getTimeout());
			} catch (EOFException eof) {
				nRead = -1;
			} finally {
				if (selector != null) {
					pool.put(selector);
				}
			}
		} else {
			nRead = channel.read(channel.getBufHandler().getReadBuffer());
		}
		return nRead;
	}
}
